by a stone：表示行为者是谁或起作用的事物是什么（石头），意为：靠，用，通过，被，由

《柯林斯词典》对 by 的注释：

1. PREP If something is done by a person or thing, that person or thing does it. 被

例：

The feast was served by his mother and sisters.

宴席由他的母亲和姐妹们招待。

例：

I was amazed by their discourtesy and lack of professionalism.

我为他们的无礼和职业精神的缺乏所震惊。

2. PREP If you say that something such as a book, a piece of music, or a painting is by a particular person, you mean that this person wrote it or created it. 由…创作

例：

A painting by Van Gogh has been sold in New York for more than eighty-two million dollars.

一幅由梵高创作的画在纽约卖到超过八千二百万美元。